1. Field of the Invention
The present invention relates to a stereo camera apparatus. More particularly, the present invention relates to an apparatus and a method for aligning images obtained by each camera mounted in a stereo camera apparatus.
2. Description of the Related Art
In general, a stereo camera apparatus is an apparatus that generates a stereoscopic image. A conventional method of generating a stereoscopic image is to obtain two perspectives of the same image, similar to the use of an eyesight difference between a human's two eyes, in other words, the right eye and the left eye, that is, a binocular disparity (hereinafter called binocular disparity). The right eye and the left eye are placed having a predetermined distance between them equivalent to the distance of the glabella so that a left image and a right image directed to the left eye and the right eye, respectively, are different from each other. Therefore, a binocular disparity occurs. Accordingly, in order to get a stereoscopic image similar to an image generated through a human's two eyes, a camera apparatus requires a left camera and a right camera which have a predetermined distance between them like a human's two eyes. Therefore, a stereo camera apparatus includes at least two cameras, in other words, a left camera and a right camera, and generates a stereoscopic image similar to a stereoscopic image generated by a binocular disparity using the left camera and the right camera which obtain perspectives of an image from different positions.
FIGS. 1A and 1B illustrates examples of images obtained by a conventional stereo camera apparatus.
FIG. 1A illustrates an example of an image obtained by a left camera of the conventional stereo camera apparatus, and FIG. 1B illustrates an example of an image obtained by a right camera of the conventional stereo camera apparatus. As shown in FIGS. 1A and 1B, the respective cameras of the stereo camera apparatus are placed a predetermined distance apart from each other so that a slight difference in position and shape of the image is obtained even though the identical object is photographed by both cameras of the stereo camera apparatus.
The above-mentioned binocular disparity does not refer to the difference of an image in the vertical direction. That is, as a left eye and a right eye are oriented differently in the horizontal direction, the binocular disparity is not caused by a difference in the vertical direction but by a difference in the horizontal direction. However, FIGS. 1A and 1B illustrate that differences of the image obtained by the cameras occurs in both the horizontal direction as well as in the vertical direction.
Those differences may occur for several reasons. For example, the stereo camera apparatus may be mishandled, or there may be manufacturing variations. Manufacturing variations may occur because, no matter how detailed the stereo camera is made, a difference in vertical location may occur when the cameras are installed. Therefore, as shown in FIGS. 1A and 1B, in the conventional stereo camera apparatus, disparities of the images in the vertical direction as well as in the horizontal direction occur so that an exact stereoscopic image may not be generated.
A manufacturer may manually readjust the locations of the stereo cameras to be aligned with the obtained images if the number of stereo camera apparatuses produced is small. However, if the stereo camera apparatus is mass-produced, it is very difficult to examine all cameras and readjust the locations of the cameras because of the enormous expense incurred and time spent to make such adjustments.